netfilter: nf_tables: reject invalid set policy

Report -EINVAL in case userspace provides a unsupported set backend
policy.

Fixes: c50b960 ("netfilter: nf_tables: implement proper set selection")
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>

Author: ummakynes

net/netfilter/nf_tables_api.c

@@ -5048,8 +5048,16 @@ static int nf_tables_newset(struct sk_buff *skb, const struct nfnl_info *info,
 	}
 
 	desc.policy = NFT_SET_POL_PERFORMANCE;
-	if (nla[NFTA_SET_POLICY] != NULL)
+	if (nla[NFTA_SET_POLICY] != NULL) {
 		desc.policy = ntohl(nla_get_be32(nla[NFTA_SET_POLICY]));
+		switch (desc.policy) {
+		case NFT_SET_POL_PERFORMANCE:
+		case NFT_SET_POL_MEMORY:
+			break;
+		default:
+			return -EOPNOTSUPP;
+		}
+	}
 
 	if (nla[NFTA_SET_DESC] != NULL) {
 		err = nf_tables_set_desc_parse(&desc, nla[NFTA_SET_DESC]);